common/vty.c: fix 'cfg_phy_no_inst_cmd' command description
common/vty.c: fix 'cfg_phy_no_inst_cmd' command description

A comma is needed to separate a command definition from its
description, not the parts of description. Let's fix this.

Before this patch:

  OsmoBTS# configure terminal
  OsmoBTS(config)# phy 0
  OsmoBTS(phy)# no?

    no  PHY Instance number

  OsmoBTS(phy)# no ?

    instance
    osmotrx   OsmoTRX Transceiver configuration

After this patch:

  OsmoBTS# configure terminal
  OsmoBTS(config)# phy 0
  OsmoBTS(phy)# no?

    no  Negate a command or set its defaults

  OsmoBTS(phy)# no ?

    instance  Select a PHY instance to remove
    osmotrx   OsmoTRX Transceiver configuration

Change-Id: If10d85abc6506118ba08c37e8101f423d6f838ea

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts